class_docstr: defines how to transform encoder to decoder
  
  # Arguments
  bridge_type: currently only support "dense | densenonlinear"
  decoder_hiddenSize: hidden size of decoder
  bridge: keras layers used to do the transformation
  
  >>> bridge = Bridge.initialize("dense", 2)
  creating: createZooKerasBridge
  >>> dense = Dense(3)
  creating: createZooKerasDense
  >>> bridge = Bridge.initialize_from_keras_layer(dense)
  creating: createZooKerasBridge
code: def __init__(self, bridge_type, decoder_hidden_size, bridge):
      super(Bridge, self).__init__(
          None, bridge_type, decoder_hidden_size, bridge
      )
  
imports: from bigdl.nn.layer import Layer
  from zoo.pipeline.api.keras.layers import *
  from zoo.models.common import ZooModel
  from zoo.common.utils import callZooFunc
  from zoo.pipeline.api.keras.engine import ZooKerasLayer
  from zoo.pipeline.api.keras.models import Model
label_desc: Use image node_id 1 to create a new Bridge object from inherited base classes: ZooKerasLayer with example: obj = Bridge(bridge_type, decoder_hidden_size, bridge)